The lists:member/2 function will return either true or false. Hence, if it does not return false, it MUST be true that is returned. It is bad style to catch-all this in general when the enumeration is bounded. Further extensions to the enumeration will, rather than fail, return something. Which can be something unwanted.
The three methods from lists: keydelete/3, keysearch/3 and foreach/2 are only referenced once in the file. By making them explicit, we simplify the readability of the code. Furthermore, this change makes the style in the file consistent. Several places prefixed calls explicitly with the lists module, while others did not. Change member/2 and foldl/3 from lists to explicit naming. This marks the complete removal of all -import() statements in the code.
We only have two references to the error logger modules format function in all of the code. By making the error_logger explicit, we help the reader of the module to understand what is going on, rather than split his knowledge and kill his reader-locality.